In a large bowl, mix shredded chicken taco meat, cooked white rice, diced tomatoes, olives, fresh cilantro, and one cup shredded Mexican cheese. Mix well and set to the side.
Fill the slow cooker with 1/3 cup water.
Rinse bell peppers, and then cut around the tops of the bell peppers removing the seeds and stem. Carefully begin filling the bell peppers with the chicken-rice mixture. Place stuffed bell peppers in the slow cooker. Top with remaining 1 cup shredded cheddar cheese. Cook on low for 5 hours. Remove bell peppers from slow cooker and serve with sliced avocado, salsa, and sour cream.